Learn Russian: Эти таблетки есть в аптеке. - These pills are available at the pharmacy.

You're right that Russian normally skips 'is' or 'are' in descriptive sentences like 'The pharmacy is big' (Аптека большая). However, when you want to express that something actually exists or is available in a location, you must use есть. In this sentence, it translates best as 'are available' or 'are in stock'.

Doesn't есть also mean 'to eat'? How do I know which meaning applies here?

Yes, есть is also the infinitive verb meaning 'to eat'. You can tell them apart by context and grammar. Here, it is the present tense form of 'to be' used for availability. If it meant 'eating', the verb would be conjugated to match the subject, such as они едят (they eat). The pattern 'Subject + есть + Location' is the standard way to say something is available.

Why is the word for 'these' Эти instead of Это?

Это is often used as a standalone word meaning 'this is' or 'these are', as in Это таблетки (These are pills). But when 'these' acts as a pointer directly describing a noun right next to it, it must match that noun in gender and number. Because таблетки (pills) is plural, we must use the plural form эти.

Why does the word for pharmacy end in '-е' here (аптеке)?